The present invention relates generally to fastening equipment and more particularly to equipment and methods for drilling holes through a workpiece, delivering fasteners to the workpiece, and installing the fasteners into the holes.
In the production assembly of aircraft, the majority of substructure such as fuselage frames and longerons, along with wing spars and ribs, are joined to the skin of the aircraft with thousands of fasteners. Further, a plurality of fastener types, along with variations in diameters and grip lengths, are typically used in an aircraft assembly or subassembly. (Generally, a fastener grip length refers to the cumulative thickness of the parts that the fastener holds together). Installation of fasteners in relatively large aircraft substructures and skins is typically performed either manually or by automated fastening equipment.
Manufacturing equipment that automatically delivers fasteners to a workpiece, or a fastening device, is typically employed in high rate production environments. The equipment generally comprises a storage device for the fasteners and a mechanism or system that transports fasteners from the storage device to the workpiece or fastening device. For example, U.S. Pat. No. 5,588,554 to Jones, the contents of which are incorporated herein by reference in their entirety, discloses a device for delivering fasteners to a workpiece comprising a suction head that removes fasteners from a storage area and delivers the fasteners through a delivery tube using a vacuum. The fasteners are individually stored in holes of a predetermined or fixed depth, and only one fastener may be stored in any given hole. Accordingly, each hole contains a fastener of a specific configuration, diameter, and grip length.
Yet another known art fastener delivery system is disclosed in U.S. Pat. No. 5,193,717 to Rink et al., wherein rivet cartridges are unloaded and rivets are delivered to a rivet machine or the like with pressurized air. The rivet cartridges are filled off line by a rivet pump that receives rivets from a vibrating bowl feeder, and the fasteners are delivered through a common passageway to a fastener installation tool. However, the fastener delivery system of Rink et al. requires a separate fastener escapement mechanism to remove and deliver the fasteners.
Additionally, manual fastener installation can be time consuming and cumbersome. Generally, an operator must first determine the appropriate fastener type and diameter from a blueprint or other manufacturing work instruction delivery system. Due to manufacturing variations in individual part fabrication and assembly positioning variations, the proper grip length of the fastener is often determined by manually measuring hole depths. Once the proper fastener configuration is determined, the fastener stock must then be located and selected from fastener bins, which are typically stored at a common location near the work station. A limited number of fasteners are then moved by hand from the fastener bins to the work station and are generally staged within the reach of an operator. If permitted by the work environment, several fasteners are stored in a pouch that is secured around the waist of an operator. Accordingly, the operator sorts through the fasteners to select the proper configuration and inserts the fastener directly into a hole through the parts or inserts the fastener into an installation tool that installs the fastener through the parts. As a result, a significant amount of time is spent by an operator determining the proper fastener configuration, locating the fastener within a storage bin, and transporting the fastener to the work station for installation. Therefore, manual fastener installation procedures are time consuming and thus costly.
Accordingly, a need remains in the art for a fastener delivery and installation system that efficiently delivers and installs fasteners to a work station or workpiece where parts are being assembled. The fastener delivery and installation system should be capable of delivering a plurality of different fastener configurations and should further be capable of automatically selecting the proper fastener configuration from a variety of inputs. Additionally, the fastener delivery system should also be capable of maintaining a record of fastener inventory that is preferably integrated with existing production manufacturing systems.
In one preferred form, the present invention provides an apparatus for delivering and installing fasteners to and through a workpiece that combines an automated machine and a fastener feed unit disposed on one side of the workpiece and a hand-held tool that is manipulated by an operator on the opposite side of the workpiece. The automated machine comprises an end effector supporting tools such as a drill for drilling a hole through the workpiece and a riveter for installing a rivet into the hole. Additionally, a controller positions and activates the automated machine, the end effector, and the fastener feed unit during operation of the apparatus.
The fastener feed unit comprises an unloading mechanism in communication with a fastener storage device, wherein a control system activates the unloading mechanism to remove a specific fastener configuration from the fastener storage device and transport the fastener to a delivery conduit, where the fastener is caused to be delivered through the delivery conduit, through the end effector, and into a hole in the workpiece, preferably using a pneumatic source. The fastener storage device is generally a fastener cassette that comprises a plurality of fastener storage tubes that house the fasteners. Each fastener storage tube houses a specific fastener configuration, which includes the fastener type (i.e. hi-lok, jo-bolt, rivet), diameter, and grip length. Accordingly, the fastener storage tubes range in diameter corresponding to the specific fastener configuration housed therein. Furthermore, the fastener storage device is removable from the fastener feed unit to facilitate ease of replacement when additional types of fasteners may be required or when the fastener storage device is moved to another apparatus. Moreover, a plurality of fastener cassettes may be used as necessary within the fastener feed unit.
The automated machine further comprises a guide structure, such as a pair of guide rails, adapted to be releasably affixed to or adjacent to the workpiece, along with an end effector carriage and a fastener carriage that travel along the guide structure and support the end effector and the fastener feed unit, respectively. Accordingly, the end effector and the fastener feed unit can be positioned in a desired location along the surface of the workpiece where a fastener is to be installed. Alternately, the fastener feed unit may be disposed at a fixed location while the end effector moves along the guide structure. The end effector further comprises an electromagnetic clamping device that generates a magnetic field and a positioning device that generates a positioning signal detectable on the opposite side of the workpiece.
The hand-held tool comprises a magnetic clamping block, such as a steel block or the like. When the magnetic clamping block is placed against the opposite surface of the workpiece on the side opposite from the end effector, the magnetic field of the clamping device causes the clamping block to be attracted toward the clamping device, thereby clamping the workpiece therebetween. The hand-held tool further comprises a detector for detecting the positioning signal of the positioning device, wherein the detector is operable to generate guidance information for an operator. Further, the hand-held tool may include a visual display for displaying the guidance information in graphical, audible, or other forms. Once the hand-held tool is aligned with the end effector, the controller activates the end effector and the fastener feed unit to drill a hole in the workpiece and to further deliver and install a fastener into the hole.
After fastener installation is complete, the end effector is operable to signal the operator that the operation is complete. The operator may then deactivate the hand-held tool such that the automated machine (and also the fastener feed unit if required) may be moved to a new location for subsequent fastener installations. Alternately, the end effector may automatically deactivate the electromagnetic clamping device once installation of the fastener is complete such that no action of the operator is required to release the clamping force on the workpiece.
As used herein, the term xe2x80x9cworkpiecexe2x80x9d should be construed by those skilled in the art to be one or more parts or workpieces that are being assembled at a given location, for example a wing spar to a wing skin, or a fuselage frame to a fuselage skin. Accordingly, the term xe2x80x9cworkpiecexe2x80x9d should not be limited to a single part or workpiece.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.